In compression molding, a mold is heated to a high temperature in order to melt and react powder-particle material. An example of an object of such compression molding in a high-temperature heating state is manufacturing of a laminar product, e.g., a separator for a fuel cell.
By the way, it is extremely important for a separator for a fuel cell to have high gas impermeability, high electrical conductivity and low profile irregularity. Although a separator of an early date is obtained by machining of a graphite plate or the like for this reason, attempts by press working are increasing in recent years upon machining time and cost request.
More specifically, mentioned above is a method for inputting a predetermined amount of powder-particle raw material into a mold and then applying heat and pressure with a pressing machine so as to obtain a laminar separator, which enables manufacturing in a shorter time and at a lower cost than one manufactured by other machining.
As affairs now stand, however, a separator which is actually manufactured still has high profile irregularity and does not reach a required level. One reason thereof is that it is difficult to distribute powder-particle raw material thinly and evenly at the entire bottom face of a female mold when inputting powder-particle raw material.
A common solution for such a problem is technique disclosed in Japanese Patent Application Laid-Open No. 2001-62858 (Patent Document 1).
More specifically, denoted at 50 in FIG. 17 is an input portion having a number of input ports 51, and denoted at 52 is a slide plate which is provided below the input portion 50 so as to be slidable between a position for closing all the input ports 51 and a position for opening all the input ports 51. Moreover, denoted at 53 is a base for supporting the input portion 50 and the slide plate 52, denoted at 54 is a bottom mold (female mold) and denoted at 55 is a top mold (male mold).
In the structure described above, powders and particles are inputted into the input portion 50 and then set in the bottom mold 54 after excess is removed by scraping with a scraping rod 56 to obtain a certain amount. Next, when the slide plate 52 is slid so as to open the input ports 51 in series from an end, the powders and particles fall into the bottom mold 54. Finally, the input portion 50 and the base 53 are moved and then pressing is performed with the top mold 55.
With the above conventional technique, it is possible to obtain a certain amount of powders and particles inputted into the input portion 50 with the scraping rod 56. However, it is difficult to improve the profile irregularity of the final product since the falling state of the powders and particles in falling from the input portion 50 into the bottom mold 54 may possibly be uneven for a certain movement speed of the slide plate.
Technique disclosed in Japanese Patent Application Laid-Open No. 2003-223901 (Patent Document 2) is known as what can prevent uneven distribution of powders and particles described above for a certain falling state at the point of falling into the bottom mold.
More specifically, denoted at 60 in FIG. 18 is a female mold and denoted at 61 is a powder supply box which is in close contact with the upper face of the female mold 60 and has a shape of frame having open upper and lower sides. Powdered raw material 62 is loaded in the powder supply box 61.
In addition, the powder supply box 61 is slid while the powdered raw material 62 is inputted into the female mold 60 and the upper face of the female mold 60 is scraped.
From what is shown in Patent Document 2, it can be understood that improvements are made to enable even input of the powdered raw material 62 into the female mold 60.
However, since the above conventional technique is for scraping the upper face of the female mold 60, scraping is impossible when the powdered raw material 62 is inputted thinly at the internal bottom face of the female mold 60.
Moreover, when the upper face of the female mold 60 is scraped, the scraped powdered raw material 62 is diffused to the periphery of the upper face of the female mold 60. Since the female mold 60 is at a high temperature during press working and even before pressing by preheating, there is a problem that the diffused powders and particles gather and attach and maintenance takes a lot of trouble.
It should be noted that a method for even filling without scraping is disclosed in Japanese Patent Application Laid-Open No. H11-49101 (Patent Document 3). More specifically, denoted at C in FIG. 19 is a container (mold) and denoted at S is a cavity.
Denoted at G is a supply hopper which is laid at the upper face of the container C, and the supply hopper G has a grid g2 at the bottom face thereof and is provided with a cover h2 at the upper face thereof. Denoted at hl is an air suction blow port provided at the cover h2. Powder P is retained in the supply hopper G.
By air tapping (repeatedly putting inside of the supply hopper G and the container C into a high-pressure state and a low-pressure state) through the air suction blow port h1 at the device, the powder P is stirred and falls evenly from the grid g2 into the cavity S. Then the powder P is separated at the face of the grid g2 when the supply hopper G is taken up in this state.
With this method, it is possible to fill powder P evenly in a mold without using means such as scraping means. However, the method cannot be applied to powder of all kinds of quality of material and, for example, resin powders and particles including carbon, such as the raw material of a separator for a fuel cell, leak and fall from the grid g2 when the supply hopper G is taken up and cannot be separated from the mold successfully.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-62858
[Patent Document 2] Japanese Patent Application Laid-Open No. 2003-223901
[Patent Document 3] Japanese Patent Application Laid-Open No. H11-49101